Melt butter in large stock pot on medium heat. Finely chop white onion, and add to melted butter with minced garlic. Saute until garlic is light brown and onions become transparent.
Add chicken stock and bay leaf, bring to a rolling boil.
Add white sweet potatoes and bullion cubes. Stir until bullion cubes are dissolved. Boil until potatoes are thoroughly cooked.
While potatoes are boiling, simmer dried mushrooms and cream in a small sauce pan. Be very careful not to scald the cream. Stir often.
When potatoes are finished cooking, add contents of large stock pot to a blender, along with the dried mushrooms (not the cream). Blend until smooth, and return to large stock pot.
Add heavy whipping cream to the blended soup, and black pepper to taste.
Garnish the Bisque
Cook bacon until half done. Dip each side of the bacon in the brown sugar, coating well.
Finish cooking bacon on medium heat, slowly letting the sugar caramelize around the meat. Bacon is done when it is hard and shiny, like candy.
Chop the bacon into small pieces, mix with chopped pecans and sprinkle on top of the soup.
Notes
Vegetarian bullion and/or broth can be substituted for Chicken. I don't recommend using beef.